The invention relates to an electronic multiple-component unit with at least a first and a second current supply contact, a substrate layer, a resistance layer disposed thereon and connected to the first current supply contact, at least one dielectric layer disposed over the resistance layer, and at least a first electrode disposed thereon and connected to the second current supply contact.
The invention also relates to a multiple-component unit with at least a first and a second current supply contact, a substrate layer, a first electrode disposed thereon, and at least a first and a second dielectric layer alternating with at least a second and a third electrode disposed on said first electrode.
Voltage supply units which are to be uncoupled from the AC signals in most applications are used in many electronic circuits. Passive components in the form of X7R capacitors, NP0 capacitors, and resistors are used nowadays in amplifier circuits for mobile telephones, in the vicinity of GaAs ICs, and for interference pulse filtering of microprocessors with high frequency clocks. Discrete X7R capacitors and discrete NP0 capacitors are connected in parallel in many circuits. Resistors are connected in parallel to the X7R capacitors in some circuits.
These passive components in amplifier circuits have the function inter alia of efficiently filtering interference frequencies from the supply lines so as to safeguard a constant supply voltage. This filtering in the range from a few MHz to a few hundred MHz is usually performed by an X7R capacitor. A resistor connected in series here has the task of preventing parallel resonances and avoiding undesired oscillations. An NP0 capacitor connected in parallel to the X7R capacitor is used inter alia to filter frequencies of a few hundred MHz, preferably the operating frequency for which the circuit was dimensioned, from the DC supply line.
The increasing miniaturization of portable electronic appliances and the increasing functionality of these systems render it necessary to miniaturize the passive components present in the circuits so as to make the circuits as small as possible.
In the present state of the art, small discrete passive components are widely used with the dimension 0402. Given a lateral dimension of 0.5xc2x71 mm2 for these components, a considerable amount of space is still required for each individual element, in spite of its small dimensions, because of its soldering onto the circuit board. At the same time, mounting of such small components is technically intricate and expensive.
A method of increasing the packing density of circuit elements is known from publication no. 03203212 A of xe2x80x9cPatent Abstracts of Japanxe2x80x9d. In this method, a capacitor is mounted on the upper surface of any passive or active component, as desired.
A further possibility for miniaturization and cost reduction is the integration of passive components in ICs.
The invention has for its object further to reduce the size of components and accordingly also of the resulting circuits and to facilitate the mounting of the components.
This object is achieved by means of an electronic multiple-component unit with at least a first and a second current supply contact, a substrate layer, a resistance layer disposed thereon and connected to the first current supply contact, at least one dielectric layer disposed over the resistance layer, and at least a first electrode disposed thereon and connected to the second current supply contact.
This arrangement has the advantage that, with a resistor and a capacitor connected in series, two passive components are realized in a single unit.
In a preferred embodiment of this multiple-component unit, a further dielectric layer and a second electrode which is connected to the first current supply contact are provided on the first electrode. Besides a resistor and a capacitor, a further capacitor has now been integrated into this multiple-component unit.
In a favorable embodiment of this multiple-component unit, the second electrode is connected to the resistance layer. The further capacitor in this embodiment of the multiple-component unit is connected in parallel to the other two components.
In a further preferred embodiment of the multiple-component unit, a second and a third dielectric layer and a second and a third electrode are provided in an alternating arrangement on the first electrode, such that the second electrode is connected to the first current supply contact and the third electrode to the second current supply contact. In this multiple-component unit, a further capacitor has been integrated, so that a total of four passive components have been combined.
In an advantageous embodiment of this multiple-component unit, the second electrode is connected to the resistance layer and the third electrode is connected to the first electrode. The second and third capacitors are thus connected in parallel to the series-connected resistance and first capacitor.
It is preferred that the resistance layer is made from a material comprising a metal, or an alloy, or a conductive oxide, or a metal and an alloy, or a metal and a conductive oxide, or a metal, an alloy and a conductive oxide, or a conductive metal nitride. After being deposited, the materials are structured into a resistance layer, for example by means of photolithographical processes in combination with wet and dry etching steps.
It may be preferred that the electrodes have a resistance value and that they are made from a material comprising a metal, or an alloy, or a conductive oxide, or a metal and an alloy, or a metal and a conductive oxide, or a metal, an alloy and a conductive oxide, or a conductive metal nitride. After being deposited on the dielectric layer, the materials are structured, for example by means of photolithographical processes in combination with wet and dry etching steps, into a resistor-like layer. In this embodiment, the multiple-component units will comprise several resistors which at the same time form the electrodes of the capacitors.
It is furthermore preferred that the first dielectric layer lying on the resistance layer has a dielectric constant value of K greater than 7. High capacitance values combined with small dimensions are achieved with this capacitor on account of the high dielectric constant value of the dielectric layer.
It is provided in the preferred embodiments of the multiple-component unit that the second and third dielectric layers have dielectric constant values of K greater than 3. The second and third capacitors have lower capacitance values.
The invention further relates to an electronic multiple-component unit with at least a first and a second current supply contact, a substrate layer, at least a first electrode disposed thereon and connected to the first current supply contact, and disposed thereon at least a first and a second dielectric layer in an alternating arrangement with at least a second and a third electrode, the second electrode being connected to the second current supply contact and the third electrode to the first current supply contact.
This multiple-component unit has the advantage that two passive components, two capacitors in this case, are realized one above the other in a single unit.
A preferred embodiment of this multiple-component unit provides that the first and the second dielectric layer are both made from a dielectric material having the same dielectric properties.
Alternatively, it may be preferred that the first and the second dielectric layer are made from dielectric materials which have different dielectric properties, the dielectric constant of the first dielectric layer being greater than the dielectric constant of the second dielectric layer.
Capacitors having the desired capacitance values and characteristics may thus be manufactured and used in dependence on the type and application of the circuit.
It is advantageous when in all multiple-component units the substrate layer comprises a ceramic material, a ceramic material with a glass planarization, a glass-ceramic material, a glass material, or silicon. A substrate layer of a ceramic material, a ceramic material with glass planarization, a glass-ceramic material, or a glass substrate can be inexpensively manufactured, so that the process cost for these components can be kept low. If the multiple-component unit is to be integrated into an IC, the substrate layer will be of silicon, possibly provided with a SiO2 passivating layer.
It may be preferred that the electrodes are made from a material comprising a metal, or an alloy, or a conductive oxide, or a metal and an alloy, or a metal and a conductive oxide, or a metal, an alloy and a conductive oxide, or a conductive metal nitride. After being deposited on the dielectric layers, these materials are structured, for example by means of photolithographical processes in combination with wet and dry etching steps, so as to form electrodes.
Each multiple-component unit can be electrically coupled to further components of the circuit at the current supply contacts, which usually lie at opposite sides of the unit. Depending on the type of application or the type of component mounting, an electroplated SMD end contact or a bump end contact or a contact surface may be used. The use of SMD end contacts, for example made from Cr/Cu, Ni/Sn or Cr/Cu, Cu/Ni/Sn or Cr/Ni, Pb/Sn, or bump end contacts renders possible the manufacture of discrete multiple-component units, whereas the use of contact surfaces enables an integration of the multiple-component units in ICs.
It may also be preferred that a barrier layer is present on the substrate layer in all multiple-component units for the purpose of avoiding reactions with the dielectric or short-circuits in the case of substrate layer materials with rough surfaces.
It may in addition be preferred that a protective layer of an inorganic and/or organic material is disposed over the entire multiple-component unit. The protective layer protects the subjacent layers against mechanical loads.
It may also be preferred that a glass layer or a glass plate is provided on the protective layer. This additional layer protects the multiple-component unit from moisture and corrosion.